Changes in periodontal fibre organization in mature bone/tooth isografts in mice.

Mature mouse mandibular third molars together with their periodontal ligaments and alveolar bone were isografted to two heterotopic sites: the renal subcapsular site and the tibial shaft medulla. The pulps and periodontal ligaments of the grafts underwent cellular degeneration after transplantation but demonstrated signs of revascularization and cellular repopulation 7 days after transplantation. Grafts obtained at 28, 60 and 100 days after transplantation demonstrated a significant decrease in the width of the periodontal ligament, a decrease in the number and organization of mature periodontal fibre bundles, the appearance of fibers arranged parallel with the root surface and a decrease in the thickness of surrounding alveolar bone. These regressive changes in the periodontal ligament were considered to be due primarily to the nonfunctional status of the teeth at the two heterotopic sites.